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Pasteurella multocida toxin (PMT) is one of the most important virulence factors of Pasteurella multocida type D. Pasteurella multocida infection has caused enormous economic losses in the pig farming industry. Although it is well known that this bacterial infection causes progressive atrophic rhinitis, its effects on other organ tissues in pigs are unclear. In this study, PMT was expressed and purified, and the cytotoxic effects of PMT on four types of swine cells, LLC-PK1, PAM, IPEC, and ST, were investigated. LLC-PK1 exhibited the highest sensitivity to the cytotoxic effects of PMT. Our studies revealed that a PMT concentration of 0.1 μg/kg can lead to weight loss, whereas a PMT concentration of 0.5 μg/kg can lead to death in mice. PMT causes damage to the intestines, kidneys, lungs, livers, and spleens of mice. Furthermore, PMT caused acute death in pigs at treatment concentrations greater than 5 μg/kg; at PMT concentration of 2.5 μg/kg, weight loss occurred until death. PMT mainly caused damage to the hearts, lungs, livers, spleens and kidneys of pigs. The organ coefficient showed that damage to the heart and kidneys was the most severe and caused the renal pelvis and renal pyramid to dissolve and become cavitated. Pathology revealed hemorrhage in the lungs, liver, and spleen, and the kidneys were swollen and vacuolated, which was consistent with the damaged target organs in the mice. In conclusion, these findings demonstrate that PMT is extremely toxic in vitro and in vivo, causing damage to various organs of the body, especially the kidneys and lungs. This study provides a theoretical basis for the in-depth exploration of the cytotoxic effects of PMT on target organs.

Pasteurella multocida, a zoonotic pathogen that produces a 146-kDa modular toxin (PMT), causes progressive atrophic rhinitis with severe turbinate bone degradation in pigs. However, its mechanism of cytotoxicity remains unclear. In this study, we expressed PMT, purified it in a prokaryotic expression system, and found that it killed PK15 cells. The host factor CXCL8 was significantly upregulated among the differentially expressed genes in a transcriptome sequencing analysis and qPCR verification. We constructed a CXCL8-knockout cell line with a CRISPR/Cas9 system and found that CXCL8 knockout significantly increased resistance to PMT-induced cell apoptosis. CXCL8 knockout impaired the cleavage efficiency of apoptosis-related proteins, including Caspase3, Caspase8, and PARP1, as demonstrated with Western blot. In conclusion, these findings establish that CXCL8 facilitates PMT-induced PK15 cell death, which involves apoptotic pathways; this observation documents that CXCL8 plays a key role in PMT-induced PK15 cell death.

Summary: Porcine reproductive and respiratory syndrome virus (PRRSV) poses a severe threat to the health of pigs globally. Host factors play a critical role in PRRSV replication. Using PRRSV as a model for genome-scale CRISPR knockout (KO) screening, we identified a host factor critical to PRRSV infection: sphingomyelin phosphodiesterase acid-like 3B (SMPDL3B). Our findings show that SMPDL3B restricted PRRSV attachment, entry, replication, and secretion and that its depletion significantly inhibited PRRSV proliferation, indicating that SMPDL3B plays a positive role in PRRSV replication. Our data also show that SMPDL3B deficiency resulted in an accumulation of intracellular lipid droplets (LDs). The expression level of key genes (ACC, SCD-1, and FASN) involved in lipogenesis was increased, whereas the fundamental lipolysis gene, ATGL, was inhibited when SMPDL3B was knocked down. Overall, our findings suggest that SMPDL3B deficiency can effectively inhibit viral infection through the modulation of lipid metabolism.

IntroductionPseudorabies virus (PRV) is the pathogenic virus of porcine pseudorabies (PR), belonging to the Herpesviridae family. PRV has a wide range of hosts and in recent years has also been reported to infect humans. N6-methyladenosine (m6A) modification is the major pathway of RNA post-transcriptional modification. Whether m6A modification participates in the regulation of PRV replication is unknown.MethodsHere, we investigated that the m6A modification was abundant in the PRV transcripts and PRV infection affected the epitranscriptome of host cells. Knockdown of cellular m6A methyltransferases METTL3 and METTL14 and the specific binding proteins YTHDF2 and YTHDF3 inhibited PRV replication, while silencing of demethylase ALKBH5 promoted PRV output. The overexpression of METTL14 induced more efficient virus proliferation in PRV-infected PK15 cells. Inhibition of m6A modification by 3-deazaadenosine (3-DAA), a m6A modification inhibitor, could significantly reduce viral replication.Results and DiscussionTaken together, m6A modification played a positive role in the regulation of PRV replication and gene expression. Our research revealed m6A modification sites in PRV transcripts and determined that m6A modification dynamically mediated the interaction between PRV and host.

To achieve reproduction, male solitary mammals need to locate females using chemical communication with high levels of precision. In the case of giant pandas, the total estrus period of females was usually 15 days each year, however, successful mating activity is finished within 3 days from respective home range. The mating pattern of giant pandas, where multiple males compete for each female requires females employ efficient systems to communicate their estrus phases. To verifying whether the scent secretions of giant pandas changes by gender and estrus progression, the microbiota and compounds in 29 anogenital gland samples from 14 individuals during estrus were analyzed by 16S rRNA sequencing and GC-MS. We show that the microbiota communities covary by gender with 4 particular compounds of scent secretions. Among 597 genera, 34 were identified as biomarkers that could be used to distinguish between different estrus phases. By bacterial-compounds co-analysis, 3 fatty ester acids and squalene compounds covaried with the development of estrus in the bacterial communities of female giant pandas. This study helps clarify how a large, solitary mammal expresses accurate information to improve the likelihood of successful reproduction by changing the composition of microbiota and odor compounds of anogenital glands during estrus.

Dental caries severely hinders efficient access to adequate energy in wildlife. Different food supplies will develop characteristic plaque, and the microorganisms of these plaque are closely related to dental health. Here, plaque samples from panda cubs with caries and caries-free were collected for 16S rRNA high-throughput sequencing. All sequences clustered into 337 operational taxonomic units (OTUs; 97% identity), representing 268 independent species belonging to 189 genera, 98 families, 51 orders, 24 classes, and 13 phyla. Two groups shared 218 OTUs, indicating the presence of a core plaque microbiome. α diversity analysis showed that the microbial diversity in plaques with caries exceeded that of caries-free. The dominant phyla of plaque microbiota included Proteobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Actinobacteria. The dominant genera included unclassified Neisseriaceae, Actinobacillus, Lautropia, Neisseria, Porhyromonas, unclassified Pasteurellaceae, Moraxella, Streptococcus, Bergeywlla and Capnocytophaga. β diversity analysis showed that the plaque microbial community structure was different between two groups. Using LEfSe analysis, 19 differentially abundant taxa were identified as potential biomarkers. Finally, function predictions analysis showed All the energy related metabolic pathways on KEGG level 2 were enriched in caries-active group. Consistent with the mainstream caries-causing narrative, our results illuminate the lack of information regarding the oral microflora composition and function within giant panda cubs.

Introduction: Pseudorabies virus (PRV) is the pathogenic virus of porcine pseudorabies (PR), belonging to the Herpesviridae family. PRV has a wide range of hosts and in recent years has also been reported to infect humans. N6-methyladenosine (m6A) modification is the major pathway of RNA post-transcriptional modification. Whether m6A modification participates in the regulation of PRV replication is unknown. Methods: Here, we investigated that the m6A modification was abundant in the PRV transcripts and PRV infection affected the epitranscriptome of host cells. Knockdown of cellular m6A methyltransferases METTL3 and METTL14 and the specific binding proteins YTHDF2 and YTHDF3 inhibited PRV replication, while silencing of demethylase ALKBH5 promoted PRV output. The overexpression of METTL14 induced more efficient virus proliferation in PRV-infected PK15 cells. Inhibition of m6A modification by 3-deazaadenosine (3-DAA), a m6A modification inhibitor, could significantly reduce viral replication. Results and Discussion: Taken together, m6A modification played a positive role in the regulation of PRV replication and gene expression. Our research revealed m6A modification sites in PRV transcripts and determined that m6A modification dynamically mediated the interaction between PRV and host. [ABSTRACT FROM AUTHOR]